Forest fragmentation drives zoonotic malaria prevalence in non-human primate hosts

Land conversion is understood to increase the risk of emergent zoonotic diseases. In simians and humans, infection risk has been linked to fragmented habitats. However, the role of fragmentation on disease dynamics in wildlife hosts is rarely quantified at macroecological scales due to the lack of systematic surveys. In Southeast Asia, non-human primates (NHPs) host Plasmodium knowlesi, a prominent zoonotic malaria. We examine reported primate P. knowlesi to investigate how landscape impacts parasite prevalence. Firstly, we conducted a meta-analysis of NHP P. knowlesi prevalence. Overall prevalence was 9.6% (CI95% 6.3-13.4), with considerable regional heterogeneity (I2=96.6%; CI95% 95.7-97.3) and high estimates in Borneo (52.4%, CI95% 22.8-81.3). Higher prevalence in NHPs shows clear spatial overlap with human infection foci. Secondly, environmental covariates were assembled from remote sensing data and statistical models were fitted to prevalence at multiple spatial scales. We demonstrate a strong relationship between forest fragmentation (20km, p<0.0001) and P. knowlesi in NHPs, suggesting that zoonotic malaria prevalence is maximised at intermediate levels of habitat complexity. Findings indicate a previously hypothesised trade-off between epidemiological and ecological mechanisms determining P. knowlesi infection in wildlife reservoirs, and that parasite prevalence in NHPs may be a key driver of human spillover risk. ### Competing Interest Statement The authors have declared no competing interest.